This "developing grant" application unites a group of 13 productive investigators in order to facilitate translation of basic research on early experience and the development of stress-sensitive neurobiological systems into preventive intervention research with young children who are growing up under conditions of adversity-in particular, children who have experienced maltreatment and relationship disruption. The investigators and pilot studies described herein cover a wide breadth ranging from animal (rodent and non-human primate) research to clinical studies of children in the foster care system. The proposed research will be conducted at 7 research sites, 2 of which involve randomized treatment trials of theoretically driven interventions for at-risk populations of infants and young children. By bringing together this diverse group of investigators we are able to address questions about early experience and stress neurobiology from molecular to social levels of analysis. The specific aims and the research designs proposed herein are based on 1.5 yrs of initial networking by our group during which time we determined that translational research in this area is likely to be productive, while noting the many questions that still need to be addressed before such research is likely to be successful. Five years of research is proposed, the outcome of which will provide the conceptual and methodological basis needed for studying the impact of early experience on stress neurobiology in randomized treatment interventions designed for infants and young children. As a component of this goal, in addition to the research proposed, we have established a significant training component to this application to enhance integration of prevention/intervention research and developmental neurobiological research in very young children.